package com.java.basis.thread.n7;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang.builder.ToStringBuilder;

import java.sql.*;
import java.util.Map;
import java.util.Properties;
import java.util.Random;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicIntegerArray;

/**
 * @author wangning
 * @create 2022-01-30 10:14
 */
@Slf4j(topic = "c.Test03")
public class Test03 {
	public static void main(String[] args) {
		Pool pool = new Pool(2);
		for (int i = 0; i < 5; i++) {
			new Thread(() -> {
				Connection connection = pool.borrow();
				try {
					Thread.sleep(new Random().nextInt(1000));
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				pool.free(connection);

			}).start();

		}
	}

}

@Slf4j(topic = "c.Pool")
class Pool {
	//1.连接池大小
	private final int poolSize;
	//2.连接对象的数组
	private Connection[] connections;
	//3.连接状态的数组 0-空闲，1-繁忙
	private AtomicIntegerArray states;

	//4.构造方法
	public Pool(int poolSize) {
		this.poolSize = poolSize;
		this.connections = new Connection[poolSize];
		this.states = new AtomicIntegerArray(new int[poolSize]);
		for (int i = 0; i < poolSize; i++) {
			connections[i] = new MockConnection("连接" + i);
		}
	}

	//5.拿出连接池的方法
	public Connection borrow() {
		while (true) {
			for (int i = 0; i < poolSize; i++) {
				//获取空闲连接，如果没哟空闲连接怎么办
				if (states.get(i) == 0) {
					if (states.compareAndSet(i, 0, 1)) {
						log.debug("borrow {}", connections[i]);

						return connections[i];
					}
				}
			}
			//没有空闲连接，当前线程进入等待
			synchronized (this) {
				try {
					log.debug("wait...");
					this.wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
	}

	//6.归还连接池的方法,
	public void free(Connection conn) {
		for (int i = 0; i < poolSize; i++) {
			if (connections[i] == conn) {
				//此处为什么使用set，而不用cas呢，因为持有conn的只有一个，不会出现线程安全
				states.set(i, 0);
				synchronized (this) {
					log.debug("free 归还连接{}", conn);
					this.notifyAll();
				}
				break;

			}
		}
	}
}

class MockConnection implements Connection {

	private String name;

	public MockConnection(String name) {
		this.name = name;
	}

	@Override
	public String toString() {
		return new ToStringBuilder(this)
				.append("name", name)
				.toString();
	}

	@Override
	public Statement createStatement() throws SQLException {
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql) throws SQLException {
		return null;
	}

	@Override
	public CallableStatement prepareCall(String sql) throws SQLException {
		return null;
	}

	@Override
	public String nativeSQL(String sql) throws SQLException {
		return null;
	}

	@Override
	public void setAutoCommit(boolean autoCommit) throws SQLException {

	}

	@Override
	public boolean getAutoCommit() throws SQLException {
		return false;
	}

	@Override
	public void commit() throws SQLException {

	}

	@Override
	public void rollback() throws SQLException {

	}

	@Override
	public void close() throws SQLException {

	}

	@Override
	public boolean isClosed() throws SQLException {
		return false;
	}

	@Override
	public DatabaseMetaData getMetaData() throws SQLException {
		return null;
	}

	@Override
	public void setReadOnly(boolean readOnly) throws SQLException {

	}

	@Override
	public boolean isReadOnly() throws SQLException {
		return false;
	}

	@Override
	public void setCatalog(String catalog) throws SQLException {

	}

	@Override
	public String getCatalog() throws SQLException {
		return null;
	}

	@Override
	public void setTransactionIsolation(int level) throws SQLException {

	}

	@Override
	public int getTransactionIsolation() throws SQLException {
		return 0;
	}

	@Override
	public SQLWarning getWarnings() throws SQLException {
		return null;
	}

	@Override
	public void clearWarnings() throws SQLException {

	}

	@Override
	public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
		return null;
	}

	@Override
	public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
		return null;
	}

	@Override
	public Map<String, Class<?>> getTypeMap() throws SQLException {
		return null;
	}

	@Override
	public void setTypeMap(Map<String, Class<?>> map) throws SQLException {

	}

	@Override
	public void setHoldability(int holdability) throws SQLException {

	}

	@Override
	public int getHoldability() throws SQLException {
		return 0;
	}

	@Override
	public Savepoint setSavepoint() throws SQLException {
		return null;
	}

	@Override
	public Savepoint setSavepoint(String name) throws SQLException {
		return null;
	}

	@Override
	public void rollback(Savepoint savepoint) throws SQLException {

	}

	@Override
	public void releaseSavepoint(Savepoint savepoint) throws SQLException {

	}

	@Override
	public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
		return null;
	}

	@Override
	public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
		return null;
	}

	@Override
	public Clob createClob() throws SQLException {
		return null;
	}

	@Override
	public Blob createBlob() throws SQLException {
		return null;
	}

	@Override
	public NClob createNClob() throws SQLException {
		return null;
	}

	@Override
	public SQLXML createSQLXML() throws SQLException {
		return null;
	}

	@Override
	public boolean isValid(int timeout) throws SQLException {
		return false;
	}

	@Override
	public void setClientInfo(String name, String value) throws SQLClientInfoException {

	}

	@Override
	public void setClientInfo(Properties properties) throws SQLClientInfoException {

	}

	@Override
	public String getClientInfo(String name) throws SQLException {
		return null;
	}

	@Override
	public Properties getClientInfo() throws SQLException {
		return null;
	}

	@Override
	public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
		return null;
	}

	@Override
	public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
		return null;
	}

	@Override
	public void setSchema(String schema) throws SQLException {

	}

	@Override
	public String getSchema() throws SQLException {
		return null;
	}

	@Override
	public void abort(Executor executor) throws SQLException {

	}

	@Override
	public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {

	}

	@Override
	public int getNetworkTimeout() throws SQLException {
		return 0;
	}

	@Override
	public <T> T unwrap(Class<T> iface) throws SQLException {
		return null;
	}

	@Override
	public boolean isWrapperFor(Class<?> iface) throws SQLException {
		return false;
	}
}